Shaved Door Replacement Transmitter replacement

Looking on how to get Shaved Door Replacement Transmitter replacement.
For my 49 Mercury.

Have older (20 years or so) remote door system. Used for 2 doors and trunk. Not sure of brand name as nothing on Door Replacement Transmitter

Back side has FCC ID HY5MX1 inside has label with 1123113.

Has four ****ons 1, 2, 3 and 4.

I see Spal sells a Remotes for the Multi-RCU 7
Shaved Door Replacement Transmitter replacement.
http://www.spalusa.com/store/main.aspx?p=itemdetail&item=MULTI-RCU7TX

But not sure if it would work with my older system

Picture of what I have, no name on it.